highly dependent on the habitat and the tracers used. The
shorter the half-life of the tracer, the higher is D B . This
result is mainly explained by the fact that some animals
are highly selective and prefer fresh organic matter.
So far attempts to find general relationships between
sediment mixing and biomass or organic carbon content
failed, indicating the strong species-specific effect of
bioturbation.
Bibliography
Berner, R. A., 1980. Early Diagenesis: A Mathematical Approach.
Princton: Princton University Press.
Boudreau, B. P., 1994. Is burial velocity a master parameter for bioturbation? Geochimica et Cosmochimica Acta, 58, 1243–1249.
Francois, F., Gerino, M., Stora, G., Durbec, J.-P., and Poggiale,
J.-C., 2002. Functional approach to sediment reworking by
gallery-forming macrobenthic organisms: modeling and application with the polychaete Nereis diversicolor. Marine Ecology
Progress Series, 229, 127–136.
Kristensen, E., Penha-Lopes, G., Delefosse, M., Valdemarsen, T.,
Quintana, C. O., and Banta, G. T., 2012. What is bioturbation?
The need for a precise definition for fauna in aquatic sciences.
Marine Ecology Progress Series, 446, 285–302.
BLACK AND WHITE SMOKERS
Margaret K. Tivey
Marine Chemistry & Geochemistry, Woods Hole
Oceanographic Institution, Woods Hole, MA, USA
Synonyms
Active vent deposit; Black chimney, White chimney;
Black smoker chimney, White smoker chimney; Hydrothermal chimney
Definition
Black and white smokers. Chimney-like edifices composed of mixtures of copper-, iron-, and zinc-sulfide minerals and calcium- and barium-sulfate minerals. They
form as very hot (up to ~400
C or 750
F) fluids exit very
young seafloor and mix with cold seawater, with the hightemperature fluids passing through channels within the
edifices into the deep ocean.
Introduction
Black and white smokers are the portions of seafloor
hydrothermal
vent
deposits
through
which
~200
C–400
C hydrothermal fluids travel and exit into
the deep ocean, <1,000–5,000 m below sea-level. The
hot fluids form as cold seawater percolates down into
young, still hot seafloor near the spreading axes of the
mid-ocean ridges and spreading centers in back-arc
basins; during its transit, the seawater exchanges heat
and undergoes chemical reactions with the young oceanic
crust. The seawater loses oxygen and sulfate, becomes
more acidic (pH decreases), and becomes enriched in
metals (e.g., Fe, Mn, Cu, Zn, Pb) and hydrogen sulfide,
and its temperature increases from ~2
C to >400
C
(German and Von Damm, 2006). The hot fluid is very
buoyant (because its density decreases to approximately
two-thirds of the original density as it is heated to
>400
C) and rises rapidly to the seafloor, exiting at
meter-per-second flow rates (Bischoff and Rosenbauer,
1985; Spiess et al., 1980; see “Hydrothermal Vent Fluids
(Seafloor)”). When the hot, metal- and sulfide-rich,
oxygen-poor fluid exits and mixes with cold, sulfate-rich,
metal-poor seawater, minerals precipitate rapidly as
chimney-like edifices and as particles within plumes
(with a smokelike appearance) above the edifice – see
Figure 1.
Discovery
Venting of hydrothermal fluids from the youngest portions
of the seafloor along the mid-ocean ridges was first
observed in 1977 along the Galapagos Rift where unusual
biological communities were found associated with warm
vent fluids (17
C, much warmer than the surrounding
2
C seawater); the presence of these warm fluids had
been predicted based on measurements of heat flow
(see “Marine Heat Flow”) and bottom seawater thermal
anomalies close to the mid-ocean ridge (Corliss et al.,
1979). In 1978, massive sulfide deposits that likely
formed from much higher temperature fluids were found
near 21
N latitude on the East Pacific Rise about 650 m
west of the spreading axis (Francheteau et al., 1979).
The first actively venting black and white smokers were
subsequently discovered in 1979, along the spreading axis
of the East Pacific Rise (Spiess et al., 1980) not far from
where the deposits were found a year earlier.
The hot fluids were observed exiting “stacks” or “chimneys” that were 1–5 m tall, composed of copper-, iron-,
and zinc-sulfide minerals and the mineral anhydrite
(calcium sulfate) (Spiess et al., 1980). The observed black
chimneys, or black smokers, resembled organ pipes
30 cm in diameter and emitted hot (>350
C) fluid with
dark-colored (black) precipitates suspended within the
exiting fluid (Spiess et al., 1980). The white chimneys,
or white smokers, were covered with worm tubes
(making them light-colored) and emitted cooler
(<330
C) fluids at slower flow rates with light-colored
precipitates suspended within exiting waters (Spiess
et al., 1980; Haymon and Kastner, 1981).
Formation of black smoker chimneys
Black smoker chimneys form in two stages (Haymon,
1983; Goldfarb et al., 1983): (1) deposition of an anhydrite
(CaSO 4 )-dominated wall as hot, calcium-rich vent fluid
mixes turbulently with cold, sulfate- and calcium-rich seawater, followed by (2) deposition of a layer of sulfide minerals against the inner side of the anhydrite layer as the
Stage 1 anhydrite wall prevents rapid mixing between
the hot fluid flowing inside the chimney and the cold
58
BLACK AND WHITE SMOKERS
shorter the half-life of the tracer, the higher is D B . This
result is mainly explained by the fact that some animals
are highly selective and prefer fresh organic matter.
So far attempts to find general relationships between
sediment mixing and biomass or organic carbon content
failed, indicating the strong species-specific effect of
bioturbation.
Bibliography
Berner, R. A., 1980. Early Diagenesis: A Mathematical Approach.
Princton: Princton University Press.
Boudreau, B. P., 1994. Is burial velocity a master parameter for bioturbation? Geochimica et Cosmochimica Acta, 58, 1243–1249.
Francois, F., Gerino, M., Stora, G., Durbec, J.-P., and Poggiale,
J.-C., 2002. Functional approach to sediment reworking by
gallery-forming macrobenthic organisms: modeling and application with the polychaete Nereis diversicolor. Marine Ecology
Progress Series, 229, 127–136.
Kristensen, E., Penha-Lopes, G., Delefosse, M., Valdemarsen, T.,
Quintana, C. O., and Banta, G. T., 2012. What is bioturbation?
The need for a precise definition for fauna in aquatic sciences.
Marine Ecology Progress Series, 446, 285–302.
BLACK AND WHITE SMOKERS
Margaret K. Tivey
Marine Chemistry & Geochemistry, Woods Hole
Oceanographic Institution, Woods Hole, MA, USA
Synonyms
Active vent deposit; Black chimney, White chimney;
Black smoker chimney, White smoker chimney; Hydrothermal chimney
Definition
Black and white smokers. Chimney-like edifices composed of mixtures of copper-, iron-, and zinc-sulfide minerals and calcium- and barium-sulfate minerals. They
form as very hot (up to ~400
C or 750
F) fluids exit very
young seafloor and mix with cold seawater, with the hightemperature fluids passing through channels within the
edifices into the deep ocean.
Introduction
Black and white smokers are the portions of seafloor
hydrothermal
vent
deposits
through
which
~200
C–400
C hydrothermal fluids travel and exit into
the deep ocean, <1,000–5,000 m below sea-level. The
hot fluids form as cold seawater percolates down into
young, still hot seafloor near the spreading axes of the
mid-ocean ridges and spreading centers in back-arc
basins; during its transit, the seawater exchanges heat
and undergoes chemical reactions with the young oceanic
crust. The seawater loses oxygen and sulfate, becomes
more acidic (pH decreases), and becomes enriched in
metals (e.g., Fe, Mn, Cu, Zn, Pb) and hydrogen sulfide,
and its temperature increases from ~2
C to >400
C
(German and Von Damm, 2006). The hot fluid is very
buoyant (because its density decreases to approximately
two-thirds of the original density as it is heated to
>400
C) and rises rapidly to the seafloor, exiting at
meter-per-second flow rates (Bischoff and Rosenbauer,
1985; Spiess et al., 1980; see “Hydrothermal Vent Fluids
(Seafloor)”). When the hot, metal- and sulfide-rich,
oxygen-poor fluid exits and mixes with cold, sulfate-rich,
metal-poor seawater, minerals precipitate rapidly as
chimney-like edifices and as particles within plumes
(with a smokelike appearance) above the edifice – see
Figure 1.
Discovery
Venting of hydrothermal fluids from the youngest portions
of the seafloor along the mid-ocean ridges was first
observed in 1977 along the Galapagos Rift where unusual
biological communities were found associated with warm
vent fluids (17
C, much warmer than the surrounding
2
C seawater); the presence of these warm fluids had
been predicted based on measurements of heat flow
(see “Marine Heat Flow”) and bottom seawater thermal
anomalies close to the mid-ocean ridge (Corliss et al.,
1979). In 1978, massive sulfide deposits that likely
formed from much higher temperature fluids were found
near 21
N latitude on the East Pacific Rise about 650 m
west of the spreading axis (Francheteau et al., 1979).
The first actively venting black and white smokers were
subsequently discovered in 1979, along the spreading axis
of the East Pacific Rise (Spiess et al., 1980) not far from
where the deposits were found a year earlier.
The hot fluids were observed exiting “stacks” or “chimneys” that were 1–5 m tall, composed of copper-, iron-,
and zinc-sulfide minerals and the mineral anhydrite
(calcium sulfate) (Spiess et al., 1980). The observed black
chimneys, or black smokers, resembled organ pipes
30 cm in diameter and emitted hot (>350
C) fluid with
dark-colored (black) precipitates suspended within the
exiting fluid (Spiess et al., 1980). The white chimneys,
or white smokers, were covered with worm tubes
(making them light-colored) and emitted cooler
(<330
C) fluids at slower flow rates with light-colored
precipitates suspended within exiting waters (Spiess
et al., 1980; Haymon and Kastner, 1981).
Formation of black smoker chimneys
Black smoker chimneys form in two stages (Haymon,
1983; Goldfarb et al., 1983): (1) deposition of an anhydrite
(CaSO 4 )-dominated wall as hot, calcium-rich vent fluid
mixes turbulently with cold, sulfate- and calcium-rich seawater, followed by (2) deposition of a layer of sulfide minerals against the inner side of the anhydrite layer as the
Stage 1 anhydrite wall prevents rapid mixing between
the hot fluid flowing inside the chimney and the cold
58
BLACK AND WHITE SMOKERS